Traffic signal



Jan. 17, 1939. P. P. HoRNl 2,144,535

TRAFFIC SIGNAL Filed Jilly 8, 1936 5 Sheets-Sheet 1 Z Relays Fig?.

3' lNvENToR PJ. /Q Mm BY /gmu En@ MY wm ATTORNEYS Jan. 17; 1939; P. P. HORN. 144,536

TRAFFI C S IGNAL Filed July 8, 1,936 5 Sheets-Sheet 2 93 f3 INVENToR ATTORNEYS P. P. HORNI TRAFFIC SIGNAL Filed July 8, 1956 5 Sheets-Sheet I5 ATTORNEYS Jan. 17, 1939.

Jan. 17, 1939. P. P. HoRNl 2,144,535

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ATTORNEYS Jan. 17, 1939.

@L by EL 1| Filed July 8, 1936 P. P. HORNI TRAFFIC SIGNAL 5 Sheets-Sheef 5 INVENTOR BYPJ- i mmwmws Patented Jan. .l 7, 1939 UNITED. STATES PATENT OFFICEY mmc SIGNAL Paul P. Horni, Newark, N. J. Application 4July s, 1936, serial No. 89,585

` 2z claims.

This invention relates to automatic trafilc regulating apparatus and is concerned more particularly witha novel apparatus of this type which is selectively operable within limits in accordance 5 with and in response to the volume and nature of the trailicpassing the street intersection where the apparatus is located, and which is subject in its operation to the iniluence of a time control. The new apparatus isespecially adapted for use with one or more similar apparatus spaced along a through tramo lane at side street intersections thereof, to provide a traic control system along the lane in which the individual control 'units vfor the intersections are operable 'in a predeter- 5 mined time phase relation but are responsive within limits to the traflic conditions prevailing in the lane and the side streets thereof.

This application is a continuation-impart of my copending application Serial No. 692,091, led October 4, 1933. (Y

For the purpose of simplicity in description, it

will be understood that the term unit as used herein refers to a single trafc control apparatus for controlling flow of trafc at a single intersection of streets, while the term "system as used herein refers to a plurality of traffic control units spaced along a through lane at street intersections thereof for controlling flow of tramo along the lane and its. side streets.

Automatic trac control systems of various forms have been devised heretofore for controlling the flow of traillc along a lane which is intersected at spaced intervals by cross streets. A common system forthis purpose is one in which the indivldual tralc control units located at successive intersections are the familiar prexed timer units which transfer the right of Way from the lane to the cross streets and back to the lane in alternation at fixed time intervals, the individual units being adjusted to operate the traflc signals either simultaneously or progressively along the lane. Another form of system includes individual tramo control units of the so-called fully actuated type in which the streets forming the int'rsection at which each of the units is installed are provided with devices responsive to traffic approaching the intersection for appropriating control of thesignals, the individual units being connected together electrically so that actuation of one of them results in corresponding actuation of the others. Still anotherform is one in which the individual traiic control units are of 'the "semi-actuated or normal go type wherein trame on the through lane retains the right of way until trame on one or more of the cross streets initiates a signal circuit common to the units, whereby the right of way istemporarily transferred to the cross streets along the lane and is then restored to the lane after the expiration of Ka predetermined time interval.

Each of these systems has certain advantages and disadvantages depending on several factors, f among which are the nature and volume of the traic negotiating the lane and the streets which intersect it, variations in the volume and nature 10 of trao during different times of the day, or at different seasons of the year, and the like. For example, the traiic regulating system in which the individual control units are of the prexed timer type is advantageous if the nature and '15 volume of the trafiic is substantially ,uniform along the through lane and the several cross streets; but if this is ynot the case the system perlodically halts traic along the through lane when there is no traflic on any of the cross streets to 20 warrant the delay, or stops traffic on the crossstreets when there is no traic on the through lane, so that congestion instead of dispatch of, the trailc results.

The system in which the individualcontrol 25 units are of the fully actuated type has distinct advantages for use along a traiiic lane where thel traic is variable on the lane and the cross streets thereof, so that neither the lane nor any of the' A cross streets could properly loe considered a 30 .main highway, and yet the though lane and cross streets pass such a considerableV amount of trafllc at certain times of the day or other periods that ythe individual control units are warranted in maintaining the right of way for,l as long a time 35 asis necessary to dispatch the traffic negotiating the through lane or side streets. However, this system has the disadvantage that it is relatively expensive to install along tralic lanes where the traillc is substantially uniform on the through 40 and side streets, because'in that event the 'sysl tem is'working most of`the time, where the less expensive systems employing pre-fixed timer units would be of greater advantage. Also, where the through trac lane passes more tralc than the 45 cross streets, it is more appropriate to maintain the right of way on the through lane so as to dispatch the heavier traiic, rather than cause the through lane traffic to initiate a signal cycle each time after cross-traveling traic has completed 50 a signal cycle permitting it to negotiate the through lane. In addition, each of the control units along the through lane which make up the system is dependent in its operation on other units in the system to vwhich it is electrically conworkpetween the units adding substantially to the cost and complexity of the system.

Systems of the type employing semi-actuated or normal go control units are vof advantage where the traffic on the Ythrough lane along which the units are`disposed isrelatively heavy as compared to the tramo along the cross streets, since" with systems of this type, heavier traic on the through lane retains the right of way at 'all times, so that it is dispatched, unless and until trailic on one or more of theA cross streets initiates the signal cycle by meansresponsive to its presence, to operate the go signals on all of the cross streets, the signalcycle upon completion restoring the rightof lWay to the through lane. However, these vsystems are not satisfactory for use,

under conditions in which' the traiilc is variable along ther through lane and side streets, nor where the trame is substantially uniform or the through lane and side streets. Moreover, as in the fully actuated systems, each of the control units which make up the system is dependent in its operation on other units in the system, the separate units beinginterconnected .by a special synchronizing network.

The present invention is directed to the provision of a novel automatic trame control unit adapted for operation in time phase relation with other similar units along a tramo lane, whereby a complete traffic control system is established along the lane having all the advantages of the systems previously described, and in addition, being capable of automatically accommodating changing tramo conditions Whether hourly, daily, or seasonal1y.- The new traffic control unit may bev'operated either simultaneously or progressively with respect to the other units along the lane,`

and when operatingin either manner it is automatically responsive within limits to `the actual Atraflic conditions prevailing on-the through lane and side street forming the intersection where the unit is locatecl.` The unit -is vcomplete and self-contained and when used in conjunction with other similar units, is independent of the other units in its operation. Accordingly, the time phase relation between the various units of a complete system may be established and maintained without the u'sual synchronizing network connected between the units. y

Thel traic control unit of this invention in- ,cludes detector devices in or adjacent the through traic lane and the cross street or streets constituting one of the intersections along the lane, the detectordevices being responsive to the presence of traflic approaching the intersection in order .to negotiate it. These detector devices,

upon. actuation by a unit of trafc,.whether vehicular or pedestrian, operate corresponding memory devices which remember thata unit of traiic'is seeking to negotiate theintersection, and accordingly appropriate control of the signal cycle to permit passage of the corresponding vehicle orpedestrian at the proper time, either upon completion of the signal cycle which was in progress at the time that the correspondingl .trahic unit actuated the detector device and Aoperated the corresponding memory device, or at a time determined by a' time-controlled mechanism to be described later. Vehicular detector devices are preferably located in the surface of the streets '"forming the intersection and the pedestrian detector devices arepreferably located at or adjacent the corners of the intersection, both 'vehicular and pedestrian detectors having memory dcnism to be described later, to permit negotiation ofthe intersection by the initiating unit of traffic at the proper time.

The memory devices, in response to actuation,l

by the trailicdetectors, energize mechanism including a selector switch which selects predetermined circuits or .mechanisms for performing various functions, depending upon prearrangement of the traic control unit and upon the nature and volume of the traffic seeking to negotiate the intersection, within limits determined by the time-controlled mechanism. For example, the selector switch prepares circuits to timing devices which determine the duration of the right of way periods for the various streets in accordance with certain predetermined factors, among which are the duration of the initial period of time during which right of way is to be maintained for pedestrian, through lane or cross street traiic, the duration of the extended period of time during which right of way is/to be maintained kto such traffic, the quantity of traillc on the respective streets, and the operation of an independent time-controlled mechanism to be described.

The initial period is adjustable in accordance with observed trafdc conditions, i. e., the initial period may be shortened or lengthened in accordance with the volume of tralc which desires to negotiate an intersection during any one signal cycle. During this initial period, the trafilc units crossing ,detector devices are rendered ineffective or prevented from interfering with the signal mechanism to appropriate control thereof, but after termination of the initial period, the actuation by other units of trame become effecy tive.

initial period, and the number of' units of time comprising the extension period is determined by tramo units following the traffic unit which originally initiated the extension period on the street which had the right of way during the previous initial period, but the maximum number of units of time by which'the extension period may be lengthened is predetermined. In other Words, within certain limits including that which may be imposed by the time-controlled mechanism to be described, the duration of the right of way on any street may be extended as many units of time after thetermination of the initial period as there are units of traiic following the trac which negotiated the intersection during the l initial period.

During theadditional units of time forming the extension period, massed tralc, single units of traffic, or any intermediate number of units of ugnit of time to further extend the extension period. That is to say, during the extension period, except at predetermined moments, the devices responsive to tralc are locked against -actuation by the traffic or are rendered ineffective to interfere with or otherwise affect the signal mechanism.

v itial and extension periods, as remembered by the corresponding `memory devices, the street previously having the rightof way maintains the right of way. If one of the memory devices has been actuated at or previous to the time when 1o the initial period expires, or when the extension period expiresif set up, the right of way is eveni'tually transferred to a pedestrian or to the street on which the initiating traiiic is waiting to cross the intersection.

The time-controlled mechanism referred to iniuences the duration of the right of way periods for cross street tramo and pedestrians, and ,also affects the duration of the right of way periods for the through lane tramo. The mechanism ino cludesa device operated by timing means, such as a constant speed motor, 'for rendering the memory devices for cross street and pedestrian traffic incapable of appropriating the right of way from the through lane to accord it to such g5 trame, except at predetermined time intervals.

Accordingly, after completion of the signal cycle for the through lane, the memory devices for pedestrian and cross street trailic, even though they have been actuated by the corresponding detector devices to remember that a correspondtime-controlled mechanism also includes a device ing traflic unit isV seeking to negotiate the intersection, must wait for the time-controlled device to operate before they can energize the mechanism for changing the trafiic right of way. The

which operates at predetermined time intervals to terminate the right of way on the through lane and accord right of way to cross street or pedestrian traic, in the event that such tramo has actuated a corresponding memoryI relay before the device operates, and under these con- 'ditions right of way will be accorded to cross street or pedestrian trafc even though extension periods are in progress on the through lane at the particular time in which the device operates.

street and pedestrian signal'operating mechanisms and includes a device which prevents appropriation ofthe right of way from the cross street untilpredetermined time intervals which on the through lane, regardless determined time intervals to accord the right of way to waiting tramo on the through lane, cross street, and pedestrian lane, respectively, regardless of other conditions, but is free to operatein accordance with prevailing trailio conditions at the intersection within the limits provided by 5 the timing mechanism.

75 signal cycle, the detector devices in the other In order to pgnvert the fully actuated ltimecontrolled trailic regulating unit just described into a semi-actuated time-controlled unit,

7d switching devices are provided whereby detector devices of the through traffic lane are disabled, and means are provided whereby the right of way is restored to the through lane either by the time-controlled mechanism or at the end of a In addition, the .mechanism eifects the 'cross f streets remaining responsive to traffic approaching the through lane in order that the right of way may be transferred to this trafiic at the proper time as determined by the time-controlled mechanism. In this way, the tramc control unit ofthis invention may be readily converted from a fully actuated unit to a semi-actuated or normal go unit, and vice versa. Also, by means of the switching devices all of the detector devices may be disabled to convert the system' into a prefixed timer system wherein right of way is alternately ltransferred from one to another and back again, in which case the imecontrolled mechanism may be disabled by other switching devices.

It will be seen that by employing a plurality of the trailic control units oil this invention along a through tramo lane at th'e cross street intersections thereof, the several units may be made to operate in a predetermined time phase relation by proper adjustment of their respective time-controlled mechanisms. That is, by adjusting the timing devices which permit the cross street and pedestrian traillc memory devices to become effective, the various control units may be prevented. from appropriating the right of way from the through lane following completion of their signal cycles until their time-controlled mechanism permit such appropriation, whereupon the right of way will be accorded to waiting traffic on the cross streets either simultaneously or progressively, depending on the relative adjustment of the time-controlled mechanisms of the respective units. By adjusting the timing devices which iniuence the cross street and pedestrian right of way'periods, the various control units may be made to return the right of way to waiting traffic on the through lane either simultaneously' or progressively, if the signal cycles for pedestrian or cross street trailic on the several cross streets have not already been completed.

It will be apparent from the foregoing that with the new traffic control unit any traffic conditions may be handled expeditiously and with precise consideration of the volume and nature of the traffic and the changes in the volume and nature of the traffic at any time. A number of the units can be mounted on any through lane at the cross street intersections thereof and readily adjusted at any time to conform to the traffic requirements of the through lane and cross streets, the trafiicon the through lane being assured of a continuous right of way across the successive intersections at the proper time intervals.

For a better understanding of the invention, reference may be had to the accompanying drawings, in which Figs. 1, 2 and 3 jointly illustrate the complete schematic circuit diagram of the selective and automatic traiiic' regulating unit of this invention, the three sheets of drawings on which these figures appear being arranged to be laid side by side to form the complete diagram;

Fig. 4 illustrates the arrangement of the initial.

and extension period counting mechanism; and Fig. 5 is a typical traffic ow diagram showing the ow'of trame along a through lane provided' with the "new control units at cross street intersection is employed merely for purposes of illusytration of the invention, it being understood that the invention is applicable with equal facility 'bou1evards, or sing-le streets which terminate in the intersection, are called streets. Thus, in Figure 3, the through street, boulevard or highway which runs north and south is'indicated as comprising two streets terminating in the intersection, and these streets are designated No. 1 street and No. 3 street, while the two east and west streets are designated No. 2` street and No.

4 street. Also, for convenience, the vhighway which runs north and south and 'comprises the No. 1 and No. 3 streets' will be referred to as a through traflic lane, and by this is meant a traffic lane which is intersected at intervals along its course by streets similar to the No. 2 and No. 4 streets, which will be referred to for convenience as cross streets.

Suitably located at the intersection and visible from all approaching streets is at least one visual signal device of conventional design. Preferably, a signal device is provided for each street of the intersection in the form of electric lights, including green, amber and red lights, although other forms and arrangements of signal means `may be employed. The lights which face No. 1 street are designated G-I, A-i and R-I; the

'lights which face No. 3 street are designated G3, A-'3 and R-3. Similarly, the lights which face No. 2 street are designated G2,.A-2 and R-Z, and thealights which face No. 4 street are designated G-, A-t and R-. Y

THE TRAFFIC DETECTINC, DEVICES Located on the right-hand sideof No. 1 street, and preferably in the surface of the roadway so as to be responsive to vehicles passing thereover,

, is a detector 50 comprising a plurality of aligned segments 5l each carrying a contact 52 normally engaging a corresponding contact 53, these contacts being connected in series with wiresiand 55. A similar vehicle detector 50' comprising aligned segments 5| is located in the surface of the right-hand side of No. 3 street. These segments 5| each control a set o'f closed contacts 52-53', which are connected in series with the contacts of detector 50 and with detector relay 56 through wires 54, 55 and 55'. These vehicle detectors are formed in segments 5l and 5I' so that more rapid,effective and simpler response by a vehicle passing over one of Nthem is obtained than if the street detector were a long strip which is necessarily bodily movable in its entirety to close the contact in response to actuation by a vehicle. As indicated and as will more fully appear, the circuits of all detectors are closed so that they cannot be short-circuited by dirt, ice,'or snow or the like accumulating between contacts as is the case with open circuit detectors, and a surer, more positive response results since it is ordinarily easier to break a circuit than to make one. Furthermore, as will be explained later, even if the detector circuits of this system are broken or the detector contacts stick open for any reason, the trame system is' not disabled but automatically becomes a "pre-fixed timer system as to the street havingl the disabled detector circuit.

Wire I55 leading to No. 1 detector relay 58 is connected through coil 51 to one side of a rectifier 58 and wire 55' is connected to the opposite side of rectifier 58. A variable resistance 5S between coil 51 and rectifier 58 varies the degree of electromotive force developed in coil 51. The input of rectiiier-f58 is connected to the secondary of a transformer B0, the primary of which is connected to a suitable source of .alternating current, such as 11o-volt lighting current conveniently obtained from supply line 6l.' In actual practice the transformer 60 delivers approximately one and one-half volt alternating current to the rectifier which converts it into approximately one volt twenty milliampere direct detectors 500 and 500 which, when actuated,

break respective closed contacts 520 and 530 or 520' and 530 connected in 'series to wires 560 and 550 leading to No. 2 detector'relay 560, which is like No. 1 detector relay 56 in every respect and is therefore not illustrated in detail.

THE SEI'ALLCTOR SWITCH Includedvin the traic regulating system of this inventionis a circuit selector switch 65, which is illustrated diagrammatically in Figure 1, and whichcomprises a shaft 66 rotatable by an eddy current motor 61, or the like, and carrying a plurality of spaced cam discs 68 each effecting the engagement and disengagement of a pair of contacts which are numbered serially from 1 to 27 on Figure 1 of the drawings for convenience. As the selector switch 65 is rotated periodically by the motor its cams 68 c lose certain of the sets of contacts and open others to select certain corresponding circuits for operation and open other corresponding circuits. Various combinations of circuits may be selected simply by adjusting the cams 5B anglarly Aon shaft B6 in a manner readily understood, means, not shown, being provided for that purpose. In the preferred arrangement, the selector switch has eight positions, in eac'n of which certain contacts are closed and the signal lights are energized in accordance with the following table:

First position Second positionr No. 1 street and No.` 3 street amber (A-I A-3) No. Zstreet and No.4 street red (R1- 2 R-4) Contacts 5-1- 8-9-I 0-2 i 2 2--21 closed.

Third position No. 1 street and No. 3 street red (R-I Fir-3) No. 2 street and No. 4 street green (G-Z Fourth position Stop No. 1 street and No. 3 street red (R-I 11,-3)

No. 2 street and No. 4 street green (G-2 No. 2 street and No. 4 street amber (A-2v In the interests of simplicity and convenience,

those circuits which are completed by the selector switch or complete circuits not including selector switch contacts will rst be described with the traic control unit or system operating as a fully actuated controller independently of the influence of the time-controlled mechanism.' which is adapted to synchronize its operation with that l.of other units,

Assume that No. 1 and No; 3 streets have the right of way, i. e., that the selector switch 65 is in the rst position indicated in the foregoing table, and that a vehicle approaching the intersection on No. 1 or No. 3 streets actuates the vehicle detector 50 or 50' to operate No; 1 detector relay 56 so that needle armature 63 engages contact 62 in the mannerv described. Since the No. 1 and No. 3 streets have the right of way, nothing happens' except that No. 1 memory relay 80 is energized by a circuit traceable from an alternating current source AC, one terminal of which is grounded as shown at GR, Wires 1| and 12, 'contact 62- of detector relay 56, needle armature 63, wire k13 or terminal' 14 where the circuit divides, one branch following wire 18 to terminal 11 where the circuit again divides, one branch leading by wire 18 to the coil 19 of No. 1 memory relay 80, the circuit of which is completed by wires 8|, 82

and 83 to the other side of the alternating current-` source AC. Armature 84 of memory relay 80 .is accordingly drawn into-engagement with froiit contacts 85 and breaks back contact 86.

The other branch circuits will be described later.

The bridging'of contacts 85 by amature 84 of memory relay 80 establishes a. holding circuit therefor, which is traceable from the alternating denser and ha resistance to suppress arcing between the delicate needle armatures and the contacts of the corresponding detector relays. The' latter are accordingly supersensitive and very accurate.

SELECTOR SWITCH Friis'r POSITION Assuming that, with the ,selector switch in the first position, No. l and No. 3 streets having the right of way, as indicated in the foregoing table, a vehicle approaching on either No. 2 or No. 4 street actuates respective vehicle detector 500 or 500', No. 2 detector relay 560 releases its needle armature to connect wires 96 ,and 91 and initiate a circuit traceable from the alternating current source AC through wires 1| and 96, detector relay 560, wire 91 to terminal 98 where the circuit divides, one branch leading by wire 99 to the coil of No. 2 memory relay |00, the circuit of which is completed to the other side of the alternating current source AC by wires 82 and 83. The armature |02 of memory relay |00 accordingly bridges front contacts |03 and breaks back contacts |04. `lilnergization of memory relay |00 completes a holding circuit for the relay and a circuit to selector switch motor 61. The holding 4circuit has two shunts, one traceable from the A alternating current source AC, wires 1| and |05,

pigtail |06, armature |02, front contact |03, wire |01 to terminal |08, branch wire |09, closed contacts I0 controlled by the follower of cam 89, terminal 98, wire 99, relay |00, Wires 82 and 83 tothe alternating current source AC; and the other shunt is traceable from terminal |08 by v wire'za tc closed contacts a cf selector switch ss,

wire 29, memory relay |00 and wires |0I, 82 and 83 back to the alternating current source AC.

The selector switch motor circuitvis traceable from the alternating current source AC through wires 1| and |05, pigtail |06, memory relay arma- -ture |02, relay contact |03, wire ||2, through closed switch 605 to wire I2', closed contact of selector switch 65, wire H3, relay ||4, and wires 5 and 83 back to the alternating current source AC. Energized relay ||4 pulls its armature ||6 into engagement with contact ||1 to complete aA 'circuit from thev alternating current source AC by wire 1|, armature H6, contact |I1, wire IIB, the poles of selector of motor 61, and wires ||9 and 83 back to the alternating current source AC.

SELEo'roaSwITcH SECOND POSITION Selector motor 61 rotates to the second position to open |-3--l4-23 contacts, close contacts 5-1-2|21, and maintain contacts 8-9' |0--22 closed, as indicated in the foregoing table. In this movement it opens the circuit of the No. l and No. 3 street green lights G--| and G3, but maintains the circuit of the No. 2 and No; 4 street red lights R-2 and R-4. The circuits of these lights are controllable by respective selector contacts 23 and 22 and are traceable from the alternating current source AC `by wires 1| and |05, pigtails |'20 and |2| of respective parallelrelays |22 and'l23, their armatures |24 and |25, their closed back contacts |26 and |21, wires |28 and |29, selector contacts 22 and 23, wire |30 leading from the former to terminal |3|, a branch wire |32, red lights R-2 and R-4, and wires |34and |35 back to the alternating current source AC,

second position in the manner described, the` green lights G-| and G-"3 signaling the right' of way to trafc on No. 1 and No. 3 streets are extinguished, but red lights R-2 and R--4 remain energized because selector contacts 22 remain closed.

The selector switch 65, in moving from rst to second position, also breaks its energizing circuit by breaking contact so that the selector switch Y 65 stops in the second position. The selector switch 65 also maintains shunt holding-circuit oi memory relay |00 closed by maintaining its contact 8 closed in moving from rst to lsecond position.

The closing of selector contacts 21 initiates a circuit traceable from the alternating current source AC, by wires 1| and |05, pigtail |20, the contacts |26 of relay |22, wire |28, terminal |41, wire |29, selector contacts 21, wire |48, terminal |49 where the circuit divides, one branch leading to parallel relays |50 and |5.|, and wires |52, 32 and 83 back to the alternating current source AC. and the other branch from terminal |49 following wire |53 to normally closed contacts |54 controlled by cam |55 of amber light motor |56, wire |51 to terminal |58 Where the circuit divides one branch following wire |59 to amber motor4 |56 l relay |5| may be traced from the alternating-curand back to the alternating 'current source AC by way of wires |60 and 83. Amber motor |56 accordingly begins to make one complete revolution when it breaks its own circuit by opening contacts |54.

The other branch from terminal |56 follows wire |6| to front contacts |62 of relay |50, which were bridged by armature |63 when the relay was energized by closure of selector contacts 21 in the manner described The armature |63 of relay |50 is connected to one side of the alternating current source AC by pigtail |64 and wires |65, |05 and 1| so that the circuit just traced constitutes a holding circuit from relay |50, which will be broken.l when caml |55 of amber motor |56 opens contacts |54.

The closure of relay I 5| establishes a circuittraceable from the alternating current source AC through wires 1|, |05 and |65, pigtail |1|, armature |12 of relay |5|,contact |13 of relay |5|,wire |14, terminal |15 Where the circuit divides, one branch traversing wire |16to terminal |11 where the circuit divides, one branch leerling to contacts |18 bridged by armature I 18 to amber light A3, and the other branch leading to contacts |19, bridged by armature to amber light AI, both light A-,I and A-3 being connected to the other side of the alternatingy current source AC by wires |44, |45, |46 and |35. Thus, the amber lights ilash a warning to. traic approaching the -intersection on No. l and No. 3 streets. y

The other branch of the circuit is-a shunt circuit including'the amber A`| and A-3 lights, wire |16, terminal |15, wire IBI, closed contacts 2| of selector switch 61, wire |29,`terminal |41, closed lback contacts |26 of relay |22, pigtail 120, and wires |05 and 1| back to the alternating current source AC. 'I'he other branch circuit from rent source AC through wires 1|, |05 and |65, pigtail |1I, armature |12, contact |13, wire |85, terminal |3| where the circuit divides, one branch following wires |32 to redrghts R-z and Rf--AJvv l back to the alternating current source AC by way of wires |34 and |35, so that relay |5| assumes control of the red lights still showing to trame on No, 2, and No. 4 streets which initiated the signal cycle being described as well as of the 5 amber lights A-I and A-3;

Energized amber motor |55 makes one complete revolution.- As it does s o it opens contact |54 to open the holding circuit for relays |50 and |5|, but these relays remain energized bel0 cause selector contact 21 remains closed. Rotation of'amber motor |56 also momentarily closes contacts |86, which complete a circuit from the alternating current source AC by wires 1|, |06 and |65, pigtail |64, armature'iGS, contacts |62, 16 lwire |66, contacts |86,-'wire |81, vclosed contacts 1 of selector switch 65, wire ||3 selector motor 61, and wires |9 and 83 back to the alternating current source AC. Selector motor 65 accordingly advances one step to the third position designated 20 on the foregoing table, the selector contactsv 4|2|1I8|9 being closed, and contacts 5-1-8-2I-22-21 being opened while. con

tacts 9 and I0 remain closed.

SELECTOR `SWITCH THIRD POSITION Opening of 'selector contacts 2|, 22 and 21 extinguishes the No. l and No. 3 street amber lights A-I and A-3 and the No. 2 and No. 4 red lights R--Z' and Pif-4, and since amber motor |55 30 breaks its own circuit the contacts controlled by l '.itscams |55, |68 and |84 are restored to their initial position which is illustrated in the drawings. Althouglrone shunt holding circuit of memory i relay '|00 is openedby opening of selector con- 35 l tacts 8, the other, shunt remains energized through closed contacts ||0 oi timing motor cam 69, and the memory relay remains closed.

The circuits selected by the selector zmotor in' its third position include two circuits, one ener- M, gizing No. 1 and No. 3 street red lights Rf-I and R-3 and the other energizing No. 2 and No. 4 street green lights G-Z and (3h-4. Selector contacts I8 and |9 control these light circuits and these circuits may be traced from the alternating 45" current source AC by way of wires 1| and |05, f Wire |65, pigtail |64 of relay |50, armature 163, back contact of relay |50, wire |93 to selector contacts i9, terminal where the circuit divides, one branchV following Wire |9| to R-I and 50 R-3 lights and by wires |44, |45, |46 and |35 back to the alternating currentl source AC. so that the red lights facing No. 1 and No. 3 streets are energized to stop the trafilc approaching the intersection on these streets which originally had 55 the right of way. The circuit from wire |93 also includesclosed selector contacts I8, wire |94 to .terminal |95 where the circuit divides, one branch traversing wire |96, relay contacts |91, relay armature I98, No. 2 street green light G-2, and 60 wires |34 .and |35 to the alternating current source AC while the other branch from terminal |95 follows wire |99 lto relay contacts200, relay armature 20|, No. 4 street green light G-4 and back to the alternating current source AC by way 65 of wires |34 yand |35. Thus, trailic approaching the intersection of No. `1 and No. 3 streets is stopped by red lights R-l and R--3 and the right of way is signaled by green lights G-2 and G-4 to traflic waiting on No. 2 and No. 4 streets, 70 which had energized vehicle detectors 500 or4 506' to initiate the signal cycle vbeing described.

l THE TIMING MEcHANIsM The duration of the signal cycle is timed from 75 now on by timing motor 202, the circuit of which is controlled by closed contacts |1 of selector switch 65. The circuit of the timing motor is traceable from the alternating current source AC, wires 1|, |05 and |65, pigtail |64 of relay |50, its armature |63, its closed back contacts, wire |93, closed contacts I1 of selector switch 65, wire 203, terminal 204 where the circuit divides, one branch following wire 205 to windings of timing motor 202 and back to the alternating current source AC by way of wires 206 and 83, so that timing motor 202 accordingly begins to revolve. The .other branch of the circuit from terminal 204 follows wire 201 to magnet 208 of limit timing mechanism and wires 200 and 83 back to the' alternating current source AC. Energization of magnet 208 causes it to draw its armature pawl 2|0 into engagement with ratchet wheel 2li, which is secured on a shaft 2|2 carrying cams 2|3 and 2|4. The cams 2|3 and 2|4 may be independently preset manually by handles 220 and 230 into any angular position relatively to each other and relatively to the ratchet wheel 2||, such as by clutching devices between the cams and the shaft 2|2, so that a greater or less time is required for the timing motor 202 to rotate the cams 2|3 and 2|4 to a point where they will close respective contacts 2|5 and 2|6, The means for rotating shaft 2| 2 comprises a star wheel or equivalent device 2|1 mounted on shaft 2|8 of timing motor 202 and arranged to engage ratchet wheel 2|| ,so as to step it through a small angle for each revolution of timing motor 202 in a manner readily understood. Armature pawl 2 0 merely serves to hold ratchet wheel 2|l| in adjusted position.

The foregoing describes the general arrangement of the initial and extension period cam mechanism in connection with the diagrammatic representation thereof fshown in Figure 2, but a more complete representation of the preferred construction of this mechanism is illustrated in Figure 4. In this arrangement the shaft 2|2 comprises three telescoped shafts, the inner one 23|, carrying extension period cam 2|3 at one end and the crank handle 230 at its other end. This crank handle carries a movable locking pin 233 at its free end adapted to be inserted in any one of a series of notches 234 formed in disc 235, exceptthe notch occupied by the locking pin 236 of initial period crank handle 220 and those notches between initial period locking pin 236 and the zero index of disc 235. By stop means, 220' the movement of initial period crank handle 220 is limited to four positions, although it may have a greater or less number of positions, de-

pending upon requirements. The extension pe-v tion.

Initial period crank handle 220 is secured on one end of `center telescoping shaft 232 having at its other end the initial period cam 2|4. This cam has a cam follower 231 controlling contacts 2|6` while extension period cam 2|3 has a cam follower 238 controlling contacts 2I5. The disc f 235 is secured on one end of outer telescoping shaft 239 having at its inner end,y the ratchet wheel 2| l, engageable by pawl 2 I 0 when the magnet 200 is energized to hold the wheel 2|| in any adjusted position against the restoring action of spring 240, which returns the cams 2|3 and 2I4, disc 235, and ratchet wheel 2|| to initial position when pawl 2|0 is released upon deenergization of magnet 208.

'I'he ratchet wheel 2H and the cams 2|3 and 2|4 are stepped or indexed angularly by pawl 2|1 on the shaft 2|8 driven through gears 24| by timing motor 202 as the latter rotates in the manner described. The speed of timing motor 202 is regulated manually by means of crank handle 242 whichpwhen moved angularly across scale 243 shifts eccentric pole pieces 244 relatively to disc armature 245. These pole pieces 244 are of the shaded laminated type, and, when shifted, their resultant torque on disc armature 245 of timing motor 202 is increased or decreased, the speed of the latter increasing or decreasing in proportion to this torque. In this way the intervals for vehicle movements on the streets are adjustable. The speed of the other motors may be adjusted4 in the same way. v

The arrangement of the 'initial period and extension period timing mechanism for No. 1 and No. 3 street traffic is precisely the same as that of'. the No. 2 and No. 4 street traflic, which has v.just been described. This mechanism appears directly above the timing mechanism just de- The timing motor 202 controls the green and red lights for all streets and when it is energized it rotates cam 2|4, which, in accordance with its angle pre-set by handle 220, determines the duration of the initial period" of operation of the signal cycle to provide the right of way to traffic which initiated the signal cycle, in this case the traffic on No. 2 or No. 4 streets. The term initial period" means that period of time during which all vehicles which follow the cycle-initiating vehicle and which pass the vehicle detectors 500 and 500', will have time to clear the intersection before the signal changes and will have no influence on the mechanism even though they actuate the vehicle detector. That is, the initial period meansy that periody oi time during which initial 'period cam 2|4 maintains its contacts 2|6 open. Until and unless contacts 2|6 are closed b y initial period cam 2|4, timing motor 202 will continue to rotate, because contacts 2|6 controlled by cam 2|4 are in the circuit of motor 61 of selector switch 65, which controls timing motor 202. The circuit is traceable from the alternating current source AC, wires 1| and |05, pigtail |06, armature |02 of relay |00, closed back contacts |04, wires 22| and 222, closed contacts I2 of selector switch 65, wire 223,- contacts 2|6, contacts 224 controlled by cam 225 of timing motor 202, wires 26 and 21, relay |4,- and back to the alternating current source AC by wire 83. Relay ||4 closes the selector motor 61 circuit and starts the latter, which then moves selector switch 65to fourth position. It should be noted that timing motor contacts 224 will notcomplete the selector motor circuit unless initial period contacts 2|6 f are closed, so that timing motor 202 must continue to rotate until such time that the feeling action of its cam 225 nds contacts 2|6 closed and this time is predetermined by the manual vsetting of cam 2|4 by handle 220.

THE EXTEN sIoN PERIOD After the sequence of operations heretofore described, and with the selector switch still-in its third position, traffic on No. 1 and No. 3 streets, or a pedestrian, cannot appropriate control of the system. However, following traffic on No. 2 or No. 4 streets may, near the end of the initial period, retain control of the signal mechanism for an additional time by setting up one or more units of an extension period. Consider the extension period. During the major initial portion of the initial period, any energization of the memory relay |00 by ,reason of following traffic in No. 2 and No. 4 streets is ineffective because of the periodic opening of the holding circuit for this relay by the opening of contacts |I0 of cam 89. However, in the final revolution of the timing shaft 2 I8 during which the initial period cam 2 I4 contacts 2|6 close, actuation of detectors in No. 2 and No. 4 streets result in setting up an extension period. Considering this final revolution of shaft 2|8, after the contacts I I0 have been opened and reclosed, thereby deenergizing memory relay |00 if energized, the reenergization of memory |00 by following tranc on No. 2 and- No. 4 streets results in preventing the energization of the selector switch motor 61 by the closing of contacts 224 at the end of the final revolution of shaft 2 I8. It should be noted that initial period cam 2|4 completes its timed revolution and closes its contacts 2|6 to prepare the circuit of selector switch motor 61 for closure by cam 225 of timing motor 202 in the manner described. However, if memory relay |00 is energized at the time that contacts 2 I6 and contacts 224 are closed, the circuit to the selector switch motor 61 is not completed in the manner described and thed selector switch does not move to fourth position, but remains in third position.

During that part of the rst extension period priorl to the momentary opening of contacts ||0,

4vehicles may cross No. 2 and No. 4street vehicle detectors 500 and 500 Without aecting the signal circuit. It is only after contacts ||0 have opened and reclosed, thus deenergizing memory relay |00, that a second additional extension period may be set up by a No. 2 or No. 4 street vehicle and this must take place before timing motor cam 225 closes the selector switch motor 61 circuit prepared by initial period cam contacts 2I6. Otherwise, selector switch 65 will be advanced to fourth position and it will be too late for a second increase of the extension period.

Assuming that a second impulse by a vehicle on No. 2 or No. 4 streets is imparted to vehicle detectors 500 or 500' between the time that memory relay |00 has been reset by timing motor cam 89 and the time that timing motor cam 225 closes the selector switch motor 61 circuit, memory relay |00 and its holding circuit will be reenergized and the second time unit of the extension period set up and. guarded against interference from other impulses in the manner described. These units of time are added to increase the extension period as often as there are actuations ofA detectors 500 or 500 in the No. 2 and No. 4 streets during lthe safety period, (that is, the period from the time that contacts ||0 have opened and reclosed to the time that contacts 224 close) until the total number of possible added units are used up as predetermined by the setting of extension period crank handle 230, the extension period cam 2 I3 being indexed one notch during each extension unit of time until it finally closes its contacts 2|5. The closing of extension period cam 2|3 contacts 2| 5 closes a circuit to selector motor 61 which is traceable from the alternating current source AC, through Wires 1|, 246, extension period cam contacts 2|5, wires 241 and 223, closed contacts 2|6 of initial period cam 2|4, contacts 224 of timing motor cam 225, wire 221. to magnet ||4 and wire 83 back to the alternating current source AC. Magnet 4 closes the selector switch. motor 61 circuit through contacts ||1 and the selector is moved to fourth position.

If there are no actuations of the vehicle detectors 500 or 500 on No. 2 vor No. 4 streets, say after the second one, when six are allowed by the setting of extension period crank handle 230. and before timing motor cam 225 completes the circuit to selector switch motor 61 through contacts 2 I6 and 224, the selector switch is moved to fourth position, and control of the signal system is taken from No. 2 andNo. 4 streets for the remainder` of the signal cycle. That is to say, there can be no more extension period units for No. 2 or No. 4 street traffic, selector switch 65 having disabled the extension mechanism by opening contacts |1.

When contacts |1 open, the initial period and extension period mechanism is reset by the resulting deenergization of pawl magnet 200, so that pawl 2|0 drops from ratchetwheel 2|| and spring 240 (Fig. 4) rotates cams 2|3 and 2|4 to their initial positions, opening contacts 2|5 and 2 I6. Also, during the last addition to the extension period, timing motor cam 89 opened contacts'l |0 to reset No. 2 memory relay |00.

SELECTOR SWITCH FOURTH POSITION It will be recalled that in the third position of tl'ie selector switch, No. 1 or No. 3 street vehicular traiiic or pedestrian traffic could not assume control of the system, although following traffic in streets No. 2 and No. 4 could set up the extension period and maintain the system in the third position. In the fourth position of the selector switch, extension. periods cannot be setup to extend the right of way period for the No.

2 and No. 4 streets, but pedestrian and No. 1 and No. 3 street traiiic can assume control.

Assume that, some time during the time that 'the right of way was transferred to No. 2 and of trac to set up the extension period, or at the end of the extension period, or at the end of some fractional part of the extension period when -there is no 'following traffic to accept the remainder of the full extension period allowed, No. 1 memory relay 80 assumes control of certain circuits set up for it by the selector switch 65. One of these circuits includes selector contact 2 and may be traced from the alternating current source AC, Wires 1| and |05, pigtail 84', armature 84 of memory relay 80, contacts 85, wire 03,

. 2,144,536 'closed switch 640, wire 93'. selector contact 2.

magnet ||4 and back to the alternating current source AC by wire 83. Magnet ||4 closes the circuit of selector motor 61 and the switch is moved to fth position.

It will be observed from the foregoing that,A

. selector contacts 8 and 9.

SELECTOR. SWITCH FIFTH POSITION In vthis position of the selector switch, contacts |8 are open and No.2 and No. 4 street green lights G-2 and G-4 are extinguished, but No. 1 and No. 3 street red lights 'Rf-I and R3 remain lighted through selector contacts |9, which remain closed. 1

The closing of selector contacts I6 energizesV amber light relays |22 and |23 through a circuit traceable from the alternating current source AC, wires 1|, |05 and |65, back contacts of relays |50 and |5 wire 248, selector contacts I6, wires 249, parallel relays |22 and |23 and back to the alternating current source AC by wires 82 and 83. The holding circuit for these relays is completed from the alternating current source AC, wires llV and |05, pigtail |20, armature |24, contacts |26',

v. wire 250, terminal 253 where the circuit divides,

one branch following closed contacts 25 of amber light timing motor 56, wire 252, relays |22 and 23 and wires 82 and 83 to the alternating current source AC. 'Ihe other branch from terminal 253 leads toamber light motork|56 and' to -the alternating current source AC by wires 254 and 83. The motor |56 accordingly begins to rotate.

The closing of relay'lza completes a circuitv traceable from the alternating current source AC, wires 1|- and ,|05, pigtail |2|,'armature |25 of relay |23, front contacts |88, wire 255, terminal 256,1where the circuit divides, one shunt'following wire 251 to relay contacts 258 and 259 to A- 2 and A44. lights and .back to the alternating current source AC by wire |35. The other shunt, through terminal 256, traverses live wires 1| and |05, the closed back contacts of relays |50 and |5|, wire 248, closed selector contacts 20, Aterminal 256 and the A'-2 and A l| lights. Accordingly, the'signal lights facing No. `2 and No.' 4 street tralc change from greento amber.

The closing of contacts 6 of selector switch 65 completes a circuity traceable from the alternating current source AC by wires 1| and |05 to pigtail 260,' back contacts26| of'pedestrian'relay 262, wire 263, closed selector contacts 6, magnet I4 and wire .8 3 b'ack to the alternating current source AC. Magnetll4 closes contacts ||1'to actuate motor 61, which moves selector switch 65` to sixth |23 remaining closed.

position.'

In this selector switch position No. 1 and No.` 3 street red ,lights R|, andlNo. 2 andA No. 4 amber lights A2A`- 4` remain yilluminated because thel corresponding selector contacts I9 vand 20, respectively, remain closed. The amber light motor |56 is still rotating, andl relays |22 and The selector switch 65 immediatelymoves to seventh 'position, the circuit to its motor '6 1 bening-traceable from the alternating currentsource -|23, which are accordingly reset.

of closed relay |22, front contact |26', wire |65, closed contacts |69 of cam |68 of amber motor |56, wire |10, closed selector contacts 4, magnet ||4 and wire 83 back to the alternating current source AC. Magnet H4 closes selector motor 61 AC, wires 1| and los, algien izo, armature m circuit and the motor rotates selector switch to f seventh position.

SELECTOR SWITCH SEVENTH PosrrIoN In this position of the selector switch. streets No. 1 and No. 3 receive the red stop signal through selector contact |9 and the amber lights A-Z and A-4 remain energized through contracts |88 of relay |23 and the amber light motor |56 continues to rotate.

The left-hand cam"|68 of amber motor |56 j momentarily closes contacts |86, completing a circuit traceable from the alternating current source AC bywires 1| and |05, pigtail |20, armature |24 of relay |22, which is still closed, its

front contact |26', wire |66, contacts |86 of y amber motor cam |68, wire |81, closed selector contacts 1, selector motor magnet ||4 and back .to the alternating current source AC by wire 83. Magnet ||4 completes selector motor 61 circuit and selector switch 65 is moved to eighth position. This completes the amber light period on streets Nos..2 and 4.

SELECTOR SWITCH EIGHTH PosrrroN In the position of the selector switch, the right of way is given to No. l and No. 3 street vehicular traic by the energization of the corresponding green lights G-l 'and G-3 through closed. se-

Closure of selector contacts 24 initiates the'circuit of timingfmotor 202, the circuit being completed by the back contacts of relay |22 when the y latter is reset by amber motorcam |55v in the relay |22 through Wires |28 and |29 to closed selector contacts 24 and by wire 350 to magnetf35| of the No. 1 and No. 3 street right of Way timer counting mechanism and to motor 202 which begins to rotate. Magnet 35| pulls its Vpawl 352 into engagement with ratchet wheel 353 to holdv the latter in anyposition to whichitis ad vanced step-by-stepby pawl or star wheel-2|1on timingmotor shaft zls.

This sets'up the initial period for theA No. 1 and No. 3 street vehicular tramo right'of way, the minimum duration of which is predeterminediby thesetting of initial periodicam 354, which is set in the same way that the initial. period cam .2|4,

' tic'aL'being illustrated in detail in Figure 4, and

'therefore it necdnot be described again.` Suice to say that, at the end of the' initial period, if no closed selector contacts initial period contacts 355, timing motor caxn 225, contacts 224, and maga' 2|8.' `This circuit may be traced from closed back contacts 86 of No.- 1 memory relay v80 through net I I 4, which energizes selector motor B1 to move the selector switch 65 back to first position.

If an extension period of the right of way for No. 1 and No. 3 streets is initiated by a following vehicle No. 1 memory relay 80 is closed, and the circuit to selectormotor 61, just traced, is brokenand remains open until the memory relay is reset by opening of its holding circuit by cam 89, contacts 90, whereupon selector motor61 advances when cam 225 contacts 224 are closed, unless all allowed units of time for the extension period are called for, whereupon extension period cam 358 closes contacts 359 t`o establish a circuit directly from the alternating current source AC by wires 1I and 246, extension period cam 358, closed contacts 359, initial period cam 354, closed contacts .355, timing motor cam 225, contacts 224, and wire 221 to magnet H4. which starts the selector motor to move selector switch 65 to rst position. The cycle is then ready to be repeated in the manner described, it4 being observed that No. 1 and No. 3 streets lstill have the normal right of way, the lights not having changed as the selector switch moved from eighth back to first position. 1

' The foregoing describes certain typical sequences of operation of the system of this invention when it arranged to be fully actuated; that is. controllable by vehicular traiilc upon any of the streets approaching the intersection to appropriate the right of way from some other street and keep it until appropriated by trafc on still another street. After the right of way has been 'maintained' on one street, say No. 1 and No. 3.

throughout the initial period and' any extension period that may be required, this right of way still remains on such street provided no approaching Vehicle on No. 2 and No. 4 streets,.or pedestrian, appropriates control. With the system in this condition, a following vehicle approaching on No. 1 and No. 3 streets may pass the intersection without effect upon the signaling system. If a vehicle approaches on cross streets N o. 2 and No. 4, actuation of the corresponding street contacts 500 or 500 results in the initiation of a signal cycle which changes the signal from green on No. 1 and No. 3 streets to amber and then to red, and changes the signals from red on No. 2

' and 4 streets to green. Thus the vehicle on No. 2 or No. 4street can proceed across the intersection and tralc on No. 1 and No. 3 streets is halted by the red lights R-I and R.-3. The right of way remains with No. 2 and No. 4 streets throughoutlthe initial period determined by the initial period cam 2I4. Dining the first portion of this 55 initial period, following traillc on No. 2 or No. 4

streets has no eect on the period during which the right of way is maintained on these streets.' However, during the last portion of this initial period, represented by that part of the last rotao tion of timing motor shaft 2I8 after contacts 90 andzyvl, I have been opened and reclosed, but beforef contacts 224 have been closed, a following vehicle on No. 2 or No. 4 street may set up a unit extension period. During the last portion of each of such unit extension periods, following vehicles may similarly set up additional unit extensionV periods until all further extensions are exhausted by the running out of cam 213 and closing oi' contacts 215. Thereafter, streetsNo. 2 and No. 4

still 'maintain the right of way if no opposing traflic approaches and if no pedestrian actuates a detector to appropriate the right of way. During the initial and extension periods, right of way cannot be appropriated by opposing tramo' or by a pedestrian.

ln order to make the system Ise'miactuated", that is, with one or more streets having the normal right of Way, which may be appropriated by a vehicle approaching on another street for a period suillcient to allow it to negotiate the intersection before the right of way isrestored to the first street, it is only necessary to close either one of the switches 310 or- 31|, depending upon which street is to have the normal right of way or normal go.

Thus, if vehicular traffic on No. 1 andi No. 3 streets is to have the normal right lof way, switch 31| is closed. This short-circuits the vehicle detectors and holds No. 1 memory relay8|l closed.

With this condition No. 1 and No. 3 street vehlcu lar traffic has the right of way unless and until it is appropriated by No. 2 and No. 4 street vehicular traiiic or pedestrian trafc, but the right of way always returns to No. 1 and No. 3 street vehicular trafc at the completion of the No. 2 and No. 4

4 street cycle or the pedestrian cycle, because No. 1

memory relay is still closed and reappropriates the right oi way.

The same condition for No. 2 and No. 4 streets takes place if switch 310 is closed. If both switches 310 and 31| areclosed, a prexed timer" system results, since, in that event,

the right of way is alternately and automatically lfor No. 1 and No. 3 streets, while the red. lights (R-2, R4) remain for No. 2 and No. 4 streets (selector switch second position). The signals change again after. a predetermined shorter .period to red (R-I, R-3) for No. 1 and No. 3

streets and green (C5-2, G4) for No. 2 and No. 4 streets. and remain for a predetermined period to give traiiic on No. 2 and No. 4 streets the right of way (selector switch third and fourth positions). 'I'he signals change again for a predetermined shorter period to amber (A-2, A-4) for No. 2 and No. 4 streets while red lights (R-I A and R-3) for No. 1 and No. 3 streets remain illuminated (selector switch ilfth, sixth .and seventh positions). The'next signal change restores the right of way to No. 1 and No. 3 streets (G-i, (3l-3) and holds traiilc stopped on No. 2 and No. 4 streets (selector switch eighth and first positions). The signal cycle is then repeated again and again. The time of each of these sig- 4 nal periods is determined by the times at which the timing motor 202, the amber light motor III. and the pedestrian and all-red motor 314 operate to step the light-controlling selector switch to the various positions indicated.

' It will be seen that the vehicular portion of tho new system is very flexible in its utility, being selectively adjustable as to timing, operation, and type of system; depending upon requirements. In addition tothe vehicular control there is a pedestrian control, which, if rendered opercontacts 4l I1 to energize selector motor 61, which l PEnEs'rarAN CONTROL Located onf'or adjacent to eachV of the four cornersof theintersection is a pedestriandetector 300 ('FigjfB),comprising a push-button treadle,

l inductanc 'oi'"capacitive detector, or the like, all

ofwhich areconnected in series and which, when actuated or jo'therwise controlled byv pedestrian traic seeking to cross one rof the streets of the ;"intersection,breaks the normally closed circuit `tectorrelay'is'precisely' like No. 1 and No. 2

to pedestrian or P .detector relay 30|. 'This devehicledetector relays 56 and 560 and therefore 'f need rit be described. The operation' of P devvtector `relay` 30| energizes 'P memory relay 262 (Fig: l); which `breaks back Ycontacts 26| and bridgesfront contactsj`30'2'with' its armature 303. This relay sets up 'ai holding circuit for itself traceable 4from the alternating current source AC Aby' wires 1I Iand |05, pigtail 260, armature 303, front contacts 302, Wire v304'to terminal 305 where the circuit divides, one branch following wire 306 to closed contact I0 of selector switch 65, which is usually closed as the table indicates, Wire 301,

vterminals 308 jand 309, v'relay 262, kand wires82 and 83 back tolthe alternating current source AC.

A shuntV of ythis holding circuit leads from aforee mention'editerminal 305 v'by"wire 3|| to closed contacts 3I2 of :cam 3|3 of pedestrian motor 3| 4,

` jwire 3|0, terminal I300,P relay 262 and back to the alternating current 'source AC by wires 02 -and 83.

moves to second position.'A

I' i Inasmuch as thefseveralpositions ofythe sei"le`cto`r switch have-been described in detail, it

will not be necessary to repeat the description of 'the effect of these positions,- except where they a'iect -the,` pedestrian control. Accordingly; Ait

r-'will'"berecalled that in thesecond'position of rotate.

"the selector switch, 'the"'No.' l and No.3 street traiiic, 'having previously Ihad the rright of way,

nis warned of a change `lcyfenergi'zation of A-"I and A-3 yamber lights andextinguishing of G- I andtG-3 greenlig'hts. These amber lights `are controlled b y selectorA contacts 21 which ccmpletes the circuitI of relays |50 and|6| and amber iight 4 motorl '15s, whichA accordingly beginsv to 'Fromfits second position, selector switch`66 rotates. practically jcoritinuously until it reaches sixth position,wherel )all streets receive amber andf'red signalsas hereinafter described, This is desirablev since. ;thevjehicular trafll must be H,stopped ,to ypermit pedestrian trailic to cross and,

therefore thevehicle rightfofway transferring -1 positions of the selectorlzswitch `can bev skipped,

i. e.,the thirdto fth positions, inclusive.,.v

.The sequence of operationsA performing ,this skippingv action begins .withfmovement .of. the selector switch l65 fromfsecondf position, where it"'made or#maintainedthe circuit ofl its motor 61`from the alternating current sourceAC, wiresV "`1"| and' |05, pigtail.|06, closed back-contacts |04 of No. 2 mem'ory relay |00;1\ closed selector con- 'tacts 5, magnet |I4 and back to the alternating use 1 1 current source AC by wire 03. It should be noted that closing this circuit requires the closing of the back contacts |04 of No. 2 memory relay |00, so that if because of the approach of the vehicle on streets No. 2 or No. 4, this relay |00 is energized, the selector switch energizing circuit will lnotbe closed and the operation of the syltem will be as described above in connection with vehicle actuation. Selector switch 66 accordingly keeps rotating to third position, where closure of'its contacts 4 maintains the circuit of its motor from the alternating current source AC, wires 1|, |06 and |65, pigtail |64 of closed relay |60,

front contact |62, wire |66, closed contacts of cam |66 of amber light motor |60, wire |10, closed contacts 4 of selector switch 66, magnet ||4, and back to the alternating current source AC by wire 83.

Selector switch 65 is accordingly rotated to fourth position from which it rotates vat once to fifth position because its motor circuit is maintained through front contacts 302 of P relay 262. wire 3|5,- through switch 6|0 to wire 3|6', and closed selector contacts 3. In the fifthv position. .the selector switch contacts I6 areiclosed but this does not energize the relays |22 and |23 because the relays |50` and I5| are energized. Similarly,

the selector switch rotates to sixth position, because a't this time, amber light-motor |66 coinpletesits rotation and momentarily closes con--` tacts |86, which, through closed selector contactsv :break the holding circuit of amber light relays |60 and |5I, so that they are reset.

In the sixth position of selector switch 66, con-Q'k tacts 26' are closed, establishing a circuit from y,the alternating current source AC, wires 6| and I 05 pigtail |20, closed back contacts of relay |22, wire |29, closed selector contacts 26, wire 3I6,

leadingby wire 3|8 to pedestrian motor 3|4 and to the. alternating currentsource AC. and the otherA branch leading to magnet 3|9 and to the alternating current source AC by wires 320, 62`

`1, maintainfthe selector motor circuit. At the .terminal 3 I 1 where the circuit divides, one branch and 83. Magnet-3|9-pulls its pawl 32|y intoen- -gagement with ratchet wheel 322 on shaft 323, carrying initial period' cam 324 and extension period cam 325,'and being driven step-by-step by periodic engagement of its ratchet wheel 322 with star wheel or pawl 326 on the shaft 321 of pedestrian motor 3I4. The arrangement, construction, purpose and operation of the pedestrian initial and extension period timing mechanism are precisely the sameas those described in connection illustrated in Figure 4, and therefore description neednot b e repeated except to add that the with the No. Zand No. 4 street vehicular trafilc 1 f control system previously described in detail `and ycounting of the initial period time until now begins and is followed by the counting of the initial period cam 324 contacts 32,8,A so` that they may cooperate with vcontactsv'o30 of pedestrian motor cam 33|l at the proper-time that'thefeelf contacts I3 are closed and prepare a circuit toing action of the lattennds the contacts 326 closed and completes the circuitto selector motor 61. Accordingly, this Acircuit is traceable from the alternating current `source AC, wires 1| and j |06, back contacts 26| of-P,y relay 262, which are closed if' there is no extension period set up, wires 263 and 332, closed selector` contacts I3, wire 333, pedestrian initial period cam 324 contacts 328, wires 334'and 221 to selector motor magnet ||4, `which accordingly closes the selector motor 61 circuit to rotate the selector switch.

-street vehicular tramo,

propriated by the pedestrian control. Thus, green lights G-i and G-3 are lighted through closed selector contacts 23, while the illumination 1f there is an extension period, the circuit isl traced from the alternating current source AC by wires 1|, |05 and 335, contacts 329 of extension period cam 325,'contacts 320 of initial period cam 324, contacts 330 of pedestrian motor cam 33|, and Wires 334 and 221 to selector motor 61 which accordingly rotates selector switch 65 to seventh position.

As in the case of the vehicular trailic timingv mechanism, the pedestrian, motor resets pedes-y trian P memory relay 262 prior to the end of the initial period and prior to the end of each unit of time of the extension periodby breaking the contacts 3|2 with cam 3|3 which opens the holding circuit of the relay. In the sixth `position of the selector switch, under pedestrian control thev red stop lights R-|, Rf-2, R-3, R-4 for. all streets and the amber warning lights A-I, A-2, A-3, A-4 for all streets aresimultaneously illuminated, the red light through closed selector contacts I9 and 22 in conjunction with back contacts oflrelays |50, .|5| and relays |22 and |23 respectively and the amber lights through closed selector contacts 20 and 2| i'n conjunction with back contacts of relays |50, |5| and relayscircuit is traceable from the alternating current source AC, wires 1| and |05, pigtail |20, closed back contacts of relay |22, wires- |28 and |29, closed selector contacts 26, wire 336, terminal 331 where the circuit divides, one branch following wire 336 to magnet 339 and motor 3|4 and the other branch leading to open contacts 340 o f cam 34|. Magnet 339 pulls pawl 342 into engagement with ratchet wheel 343 on shaft 344 carrying cam 345 controlling contacts 346. Shaft 344 and cam 345 are rotated by star wheel or pawl 326 on motor shayft 343.

In the seventh position of the selector switch 65.v the red lights forall streets are illuminated through closed y selector contacts vI9 and 22 and the back contacts of relays |50, |5| and relays |22, |23 respectively, and

of R-2 and R,-4 red lights for No. 2 and No. 4 street vehicular tramo is-A maintained through closed selector contacts 22.

The duration of the No.1 and No. 3 street right of way is determined by Vtiming motor 202 which is energized through closed selector contacts 124 by a circuit traceable from the alternating current source AC, wires 1| and |05, closed back'contacts of relays |22 and |23, wire |29, closed selector contacts 24, wire 350, pawl mag-f net 35| and timing motor 202 back to the alternating current source AC. The motorV 202 begins to rotate, pawl 352 engaging the ratchet.

wheel 353,to hold it in the positions to which it is indexed by pawl or star wheel 2 I1 on the timing' motor shaft 2|6.

The predetermined initial period is xed by initial period cam 354 in the manner described in connection with the other timing devices, closing contacts 355 at the end of its travel, so that cam 225 of timing motor 202 may close Lcontacts 224 to complete the circuit to the sefrom which it was aplector motor 61.- This circuit is traced from the 226 and 221 to magnet ||4 and back to the aiternating current source AC. The selector accordingly rotates to iirst position, unless an extension period s set up at the proper time, i. e., after contacts 0 yopen and close and before timing motor cam 225 contacts 224 close to complete the selector motor circuit. This is accomplished by energization of No. 1 memory relay 80 by a vehicle engaging detector 50 or 50', and

breaks the circuit just described through selector contacts by breaking its feed through tension period, and extension period cam 353' controlling contacts l359 for No. 1 and No. 3

street vehicular tralc operates in thev saine wayand need not be further described.

It will be seen that the pedestrian control actuates the selector switch in a diierent way than the vehicular control. causing the selector l the duration .of their illumination is deter-l mined by the` cam 345, and allows pedestrians ample time to cross, while all vehicular traillcis halted. 'I'he cam 345 isadjustable in the same way that the cams of the counting mechanism of the vehicular traiiic control systems are adjusted, and controls the period during which the traffic lights are all red. As in the other arrangements mentioned, upon closing'of the contacts 346 by cam 345 at the' end of the predetermined all-red period, a circuit is completed from the alternating current source AC by wires 1|, |05, 335 and 341, contacts 346, wire 348, contacts 330 when they are closed by cam 33|, and wires 334 and 221 to selectorrmotorl 61,

whichaccordingly rotates to eighth position.

switch to skip such positions as are not required for the pedestrians signals. This skipping lis performed rapidly, but the vehicular traillc is given sumcient time to stop on all streets forming the intersection before the period for pedestrian crossing begins, thus period being predetermined initially by the setting of the initial period cam 324 and being conti'nuable with predetermined limitsby the setting up of unit extension periods by'the eactuation of pedestrian.

` destrian motor cam contacts 330 and 3I2, in the presetting o! cam 325. r

In the eighth position of selector switch 65, the'right of' way is restored to No. 1 and No. 3

If, for any reason, it is desirable'to give the pedestriansy the normal walk" signal, switch 'A-t lights illuminated,` just as though a pedestrian held one of contacts 300 open continuously.

It should be noted that the traiiic lights energized in the sixth and seventh position of the selector switch differ depending on whether the control is set up by a vehicle yor a pedestrian. Thus, the sixth position, whereas under vehicle control the lights R-I and R-3 and A2 and A-- are lighted, under pedestrian control, all of the red and amber lights are energized. Also in the seventh position, whereas under vehicle control the lights R-I and R-3 `and. A--2 and A-d were energized, under pedestrian control, all red lights are energized. This dierence in operation between vehicular and pedestrian control is due to the fact that in positions six and seven, under vehicular control, amber light relays I22 and I23 are in their energized positions, vwhereas under pedestrian control in these positions, these relays are in their deenergized positions.

- Considering conflicting endeavors to appropriate control, if with the se1eotor switch in the nrst position, a pedestrian and a vehicle on streets No. 2 and No. 4, for example, simultaneously actuate their detector devices, the vehicle will switch in ,the fourth position, in this case if a pedestrian and a vehicle on streets No. 1 or No. 3, for example, simultaneously actuate detectors, the pedestrian will take precedence and the selector switch will continue to 'the sixth position, the No." l and No. 3 street memory relay IV being maintained energized .and appropriating right of way to streets No. 1 and No. 3 after the termination of the'pedestrian interval. 'I'his means that when a coniiict occurs, the system accords right of way to either the pedestrian or the vehicle depending upon which position the selector switch may occupy at the time the con- `iiict arises.

Also, while the pedestrian control has been described as an integral part of the tramo regulating system of this invention, it may form a separate unit if desired, ,since it is independently operative. A

` TIME CONTROL Mncnmsin 'I'he foregoing describes the construction and operation of that part of the tramo control unit of this invention which provides for theperation of the trafc signalling devices in accord- -ance with the actual volume and nature of the traffic at the particular intersection where the unit\or system is located, subject only to the limitation imposed 'bythe extension period vmechanisms which limit the'number of extension periods for ,through lane, crossstreet and pedestrian traffic. However, in cases Where a plurality of trailic control llmt a?? B9 be 1.15@

along the course of a through traic lane, as at successive intersections thereof by cross streets, it is desirable that each of the units be operable in a predetermined time phase relative to the other units in order that traiiic on the through lane may negotiate the successive intersections according to a predetermined plan. The mechanisin 'by which the new traiilc control unit is made to operate in a predetermined time phase, whereby a plurality of the units may be synchronized, will now be described.

'I'he switch 605, as previously described, completes the motor circuit of selector switch 65 through closed contact l when the selector switch is in its first position and the No. 2 memory relay is closed, the circuit beingtraceable from the AC source through wires 1I and I05, pigtail |06, memory relay armature I02, relay contact m3, wire IIE, switch 605, wire IIZ, closed contact I of selector switch 65, wire II3, relay iid, and wires H5 and 83 back to the AC source.n`

tor 601 may be of the electrically-driven synchronous type and is connected to a suitable source of current, such as 11G-volt lighting cur- A rent conveniently obtained from supply line 608.

Accordingly, when the switch 605 is opened, cam

actuated contacts 603 are connected into the selector switch motor circuit just traced, in place of switch 605, and the circuit will not be completed until the constant speed motor 601 moves cam 606 to a position .for closing the contacts.

Similarly, the switch 6H), which as previously described completes the selector .switch motor circuit throughclosed contact 3 when the selector switch is in its rst position and pedestrian memory relay P is closed, is connected through wires 6I I and 6l2 to normally open contacts 6I3. Contacts 6I3 are adapted to be closed at predetermined time intervals by a cam 6M which is preferably mounted on the shaft 606 driven by constant speed motor 601. It will be apparent that when switch 6I0 is opened, contacts 6I3 will be connected into the selector switch motor circuit including closed contact 3 and P memory relay, inplace of switch 6I0, the circuit being now traceable from the AC source through wires 1I and I 05, pigtail 260, armature 203 of P relay 262, frontcontefcts 302, wires 3I5 and 6H, contacts 6I3, Wires 612 and 3I5' closed selector contact 3, wire H3, relay IM, gand wires H5 and 83 back to the AC source. Accordingly, the circuit just traced will always remain open until such times as the constant speed motor 601 moves cam 6I@ into position for closing the contacts SIS.N

Connected to Wire 223 which leads to extension and initial period contacts2l5 and 2I6, respectively, is a Wire 223' leading to one terminal of contacts SI5. The other terminal of contacts 6I5 is connected by wires 6I6 and 6I1 to the positive side of the AC current source. Contacts @I5 are adapted to be closed at regular intervals by cam 6I8 mounted on cam shaft 606. Thus, when cam 6I8 closes its contacts I5, current will be supplied from the AC source through wires 6I1,L6I6, contacts` SI5 and wire 223 to the wire 223. 'Closure of contacts 6I5 is eiective only when the selector switch is in the third position, because it is in this position that extension and initial period cams 2I3and 2M, respectively. op-

' a closed position for a predetermined period of,

erate to rset up initial and extension periods for cross street traflic. Assuming that the selector switch is in the third position and that the initial period has ended so that contacts 2|6 are closed,

fourth position. The circuit to the selector motor switch is traced from wire 223' through wire 223, contacts 2|6 and 224, Wires 226 and 221 to electromagnet ||4 which is connected to the negative side of the AC source through wire 83. Thus, assuming that the selector switch is in the third position wherein initial and extension period cams 2|4 and 2|3 are operated, when the initial period is terminated by cam 2|4, closure of contacts 6|5 will move the selector switch into the fourth position uponclosure of contact 224, regardless of whetherthere is sufliclent traiiic on the cross street to set up additional extension periods.

Connected to wire 351 which leads to initial and extension period contacts 355 and 359, respectively, for the through lane, is a wire 351' leading to one terminal of contacts 620. The

other terminal of contacts 620 is connected by wires 62| and 6|1 to the positive side of the AC source. Contacts 620 are adapted to be closed at regular intervals by a cam 622 mounted on cam shaft 606, the closure of these contacts supplying current to wire 351 through wiresy 6|1, 62|, contacts 620 and wire 351'. It will be observed that when the selector switch is in the eighth position wherein the initial and extension period cams for the through lane are in operation, closure of contacts 620 will cause the selector switch to move into its first position, assuming that the' initial period determined by cam 354 has terminated, regardless of whether tramo on the through lan'e continues to maintain memoryy relay No. 1 in its closed position. Current for operating the selector motor switch ||4 to move the selector switch to the first position will be supplied from wire 351'4 through contacts 355 and 224, and wires 226 and 221.

Referring to the pedestrian trame timing mechanism, a wire 333' is connected to wire 333 which leads to the initial and extension period contacts V328 and 329, respectively. Wire 333' leads to one terminal of contact 630, the other terminal of which is connected through wires 63| and 6| 1 to the positive side of the AC source. A cam 632 is mounted on cam shaft 606 and is arranged to close contacts 630 at regular time intervals. Closure of contacts 630 supplies current to wire 333 from the AC source through wires 6|1 and 63|, contacts. 630 and wire 333'. Thus, when the initial period for pedestrian traffic has terminated and contacts 328 have closed, closure of contacts 630 will cause the selector switch to move from the sixth to the seventh position immediately upon closing of contacts 330, regardless of whether the pedestrian memory relay is still closed. 'Ihis is so because closure of contacts 630 supplies current to the selector motor switch ||4 through wire 333', contacts 328 and 330 and wires 334 and 221.

A Connected to the terminals of switch 640 are wires 64| and 642, respectively, whichV lead to normally opened contacts 643, these contacts being controlled by cam 644`inounted on cam shaft 606. Cam 644 is arranged to close its contacts at regular time intervals andmaintain them in time. It win be reoaued that switch 64u 1n its opened, contacts 643 will be included in the circuit for moving the selector switch from the fourth position, and if the selector switch should move into the fourth position before contacts 643 are closed it will be compelled to remain in that position until contacts 643 close.

It will be apparent from the foregoing that when switches 605 and 6|0 are opened, cams 604 and 6|4 of the time-controlled mechanism serve to prevent movement of the selector switch from its rst position with resultant appropriation of the right of way from the through lane until a predetermined time after the beginning of the normal cycle on the through lane, that is, until cams 604 and 6|4 close their respective contacts.

Also, when switch' 640 is opened, the time-controlled mechanism serves to prevent movement of the selector switch from its fourth position with resultant appropriation of right of way'from the cross street, until a predetermined time in the cycle of the unit, that is, until cam 644 closes its contact. Cams 6|8 and 632 serve to terminate the extension period for cross street and pedestrian traffic respectively at predetermined points in the cycle, in the event that such extension periods are in progress when the cams close their respective contacts. In practice, cam 6|8 is arranged to close its contacts before cam 632 closes its contacts, so that pedestrian right of way may always be accorded in every cycle for at least contacts 6|5 by cam 6|8 and `closing of contacts 630 by cam 632. Upon closing of contacts 630, which is arranged to take place after the initial period for pedestrians, the selector switch will immediately move from the sixth to the eighth position and being a new cycle, assuming that No. 1 memory relay is closed. Thus, closure of contacts 630 will mark the beginning of a new cycle, that is, will mark the time at which the selector switch moves to the eighth position to return right of way to waiting traiiic on the through lane. In the event that extension periods for the through lane are in progress when cam 622 closes its contacts, 'the selector switch will move immediately upon closing of contacts 620 to the first position and then to the third position to accord right of way tov cross street tralc, assuming that such traic has closed No. 2 memory relay.

' A Within the limits outlined above, however, the

traiiic control unit is free to operate in the usual manner according to the nature and volume of traffic at the intersection. That is, if there is no traic waiting to negotiate the intersection when the selector switch moves into one of its rest positions, i. e., its first or fourth position, the

and before cams 6|8, 632 and 622 respectively,

close their respective contacts. Thus, assuming that theV selector switch is in the eightnposition wherein right of way is accorded to the through streets Nos. 1 and 3, the switch will remain in this position until the end of the initial period,

s 35A substantially all of the period between .closing oi' or, if tranic 'on 'the through lane sets up exten;

closure of the latter contacts will move the switch to its rst position even though the maximum number of extension periods have not elapsed.

If neither cross street memory relay 800 nor pedestrian memory relay 262 has been closed in response to corresponding traiic, the selector switch will remain in the first position, thereby continuing right of way to the through lane, until one of the relays is energized. However, closing of either the cross street or pedestrian memory relays will not energize the selector motor 6l unless and' until one of the time-controlled contacts 603 and 6I3, in circuit with the closed contacts of its corresponding memory relay, is closed.l

When this occurs, the selector motor will be energized by one of the circuits previously traced, including selector contacts l and 3, and the selector switch will move into the second position.

The selector switch 65 passes through the second position in the manner previously described and upon reaching the third position, assuming that a traflic unit on the cross streets has energized No. 2 memory relay, accords the right of way to No. 2 and No. 4 streets and sets the initial and extension period mechanisms for these streets into operation. Regardless of other conditions, right of way will be maintained on the cross street for the initial period determined by cam 354. Upon closure of initial period contacts 355 right of way may be continued on the cross street by actuation of the extension period mechanism by following traiiic, but right of way will be terminated by closure of extension period contacts 350 and will be terminated before closure of these contacts if cam 622 should rst close its contacts, which would be the case if the initial period for cross street trafc were to begin later than the usual point in the cycle. If following traiiic on the cross street fails to set up extension periods, the selector switch will move to the fourth position in the usual manner, but will be prevented from moving into the fifth position until cam 644 has closed its contacts. When contacts 643 close.

with the selector switch in the fourth position, the switch will immediately move to the fth position providing that either the pedestrian or throughjlane memory relay isenergized, and if neither of these relays are energized, the switch will remain in the fourth position until such energizing occurs.

The selector switch passes through the fth position in the manner previously described and upon reaching the sixth position, assuming that a pedestrian has energized the pedestrian memory relay, accords the right of way to pedestrian traic and sets the initial and extension period mechanism for such tramo into operation. Regardless of other conditions, right of way is accorded pedestrians for Athe initial period determined by cam f 32B. Thereafter, the selector switch will move to the seventh position upon closure of pedestrian extension period contacts `320, closure of time-controlled contacts 630, or failure of pedestrian traiiic to set up additional extension periods, whichever occurs rst.

The selector switch will pass through the seventh` position in the usualmanner and return' to the eighth position where right or way will again be accorded to the throughlane'anda new cycle will begin.

It will be observed that with the new traflic control unit the time-controlled cams 6|8 and 632 may be adjusted relative to time-controlled cams 604 andv 6| 4 to assure the return of right of way to traffic' on through streets land 3 at any predetermined time after closing of contacts 603 and 6|3 and appropriation of the right'of,` way, from the through streets, and cams 604 andy 6M, assure the right of way towaiting tramo.

on the through lane for a predetermined period# regardless of other conditions. Also, the timecontrolled cams 604, 6M, 6l8, 622, 632 and 644i,`

phase, whereby several of the units placed along a through lane may be operated either synchronously or progressively as determined by the relative position of their respective time-controlled cams. Thus, by adjusting the cams 600 and Gld on a plurality of the units so that they will all operate simultaneously to close their respective contacts at predetermined time intervals, as determined by the respective constant speed motors 601, the right of Way will be maintained along the through lane simultaneously by the units at successful intersections thereof and will not be appropriated from the through lane until a predetermined time, and by adjusting the cams 6l8 and 632 on the units so that they close their respective contacts simultaneously, the right of way will be returned to the through lane at successive intersections thereof at substantially the same time if it has not already returned thereto, independently of the time-controlled mechanism. By adjusting cams 622 of the units to close their respective contacts simultaneously, the extension periods for the through lane at successive intersections will terminate at the same time thereby permitting transfer of the right .of way to the successive cross streets at substantially the same time, and by adjusting cams 640 of the respective units to maintain their contacts closed over coextensive periods of time, right of way for traic on successive cross streets may he assured over co-extensive periods of time. Obviously, by adjusting the time-controlled cams of the several units along the lane to close their respective contacts at different times, the units may be made to operate progressively along the lane, or the like.

In order to point out more clearly the advantages of the new trafiic control unit, I have shown in Fig. 5 a typical traiiic ow diagram representing the ow of traic under various traflic conditions along a through lane X provided with a control unit T of the present invention at each of the intersections thereof formed byA cross streets A, B, C, D, E and F. The time 

